When we open a web page, the style sheets cascade into a single sheet. If there are conflicts, the last-read style will be used.

<html>
<head>
<link rel="stylesheet" type="text/css" href="style.css">
<style>p { color:blue; font-size: 14px; }</style>
</head>
<body><p>I need CSS treatment.</p><p style="color:red;">Me too.</p>
</body>
</html>
]]>

See how there's no yellow text? That's because the internal style sheet overrides the external one, leaving the final color as blue.

That might not be the best way to change the color.